In a glassware forming machine of the so-called `individual section` type, the need arises to move certain operative members between out of the way positions and operative positions in which the operative member is aligned with an opening of a mould cavity of the machine. For example the machine comprises a blank mould in which parisons are formed and it is necessary to move a funnel into alignment with the mould opening so that it can guide a gob of molten glass into the mould cavity and then into an out of the way position to allow a baffle to be positioned on the mould. The same situation arises with regard to the baffle in relation to the blank mould and with regard to a blowhead in relation to a blow mould in which the parisons formed in the blank mould are blown into containers by air supplied through the blowhead.
Conventional mechanism for moving such an operative member in an individual section type machine comprises a piston and cylinder assembly having a vertically extending piston rod which projects in both directions from a piston. One end portion of the piston rod carries a horizontally extending arm on which the operative member is mounted. The other end of the piston rod carries a cam which is engaged in a spiral cam track. The arrangement is such that, when the piston and cylinder assembly is operated, the piston rod moves vertically causing the operative member to move vertically. As this movement takes place the cam track causes the piston rod to turn about its longitudinal axis thereby swinging the arm and the operative member about this axis. The operative member is thus moved in a movement which has a rotary component about the longitudinal axis of the rod and a linear component in a vertical direction.
Mechanisms of the above type are shown for example in U.S. Pat. Nos. 3,630,709, 3,986,858 and 4,120,683.
Mechanisms of the above type suffer from certain short comings. The swinging movement for the operative member is determined by the precise shape of the cam track. Consequently it is not readily capable of adjustment, and it is difficult, particularly because the swinging movement is achieved within a fairly short stroke of the piston, adequately to cushion the swinging movement of the operative member. The moving means is also prone to develop vibrations if the shape of the cam track and the speed of movement of the piston are not accurately correlated.